• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.5
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• pp.19-26
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• 2013

This study was carried out to provide preliminary data for increasing biodiversity in agricultural ecosystem and investigate availability of using Tubificidae spp. for environment-friendly agriculture through the survey of growth of Tubificidae spp. in flooded paddy fields during winter. We estimated the number of Tubificidae spp. in rice paddy where had been flooded during the previous winter in Ganghwa-gun, Suwon-si, and Hwaseong-si (Bongdam-eup and Paltan-myeon) between March and April from 2010 to 2012. During growing period of rice, the number of Tubificidae spp. was compared between flooded and non-flooded paddy field in Ganghwa-gun. As results, mean density of Tubificidae spp. in winter flooded paddy field was 7,235.5 $ind./m^2$ in Ganghwa-gun, 14,347.5 $ind./m^2$ in Suwon-si, 59,989.9 $ind./m^2$ in Bongdam-eup, and 2,610.6 $ind./m^2$ in Paltan-myeon. Mean density of Tubificidae spp. was the highest in flooded paddy fields of Bongdam-eup that was kept wet until rice harvest time and had shallow water. While mean density was the lowest in Paltan-myeon where had deep water and later flooded paddy field than others. In Ganghwa-gun, during growing period of rice, mean density of Tubificidae spp. in flooded paddy fields (171,109.0 $ind./m^2$) and flooded fallow paddy fields (321,084.2 $ind./m^2$) was much higher than non-flooded paddy fields (1,006.6 $ind./m^2$). Flooded paddy field during winter can help increase the number of Tubificidae spp. which can control weeds and enhance biodiversity in paddy fields for environment-friendly agriculture. Early flooding and shallow water of paddy fields could be a good agriculture practice to encourage the growth of Tubificidae spp..

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.271-277
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• 2015

Anaerobic decomposition of organic material in flooded rice fields produces methane, which escapes to the atmosphere primarily by transport through the rice plants. The annual amount of $CH_4$ emitted from a given area of rice is a function of the number and duration of crops grown, water regimes before and during cultivation period, and organic and inorganic soil amendments. Soil type, temperature, and rice cultivar also affect $CH_4$ emissions. The field experiment was conducted for three years to develop methane emission factor for water regime before the cultivation period from the rice fields. It was treated with three different water regimes prior to rice cultivation, namely: non-flooded pre-season < 180 days, non-flooded pre-season > 180 days, flooded per-season in which the minimum flooding interval is set to 30 days. Methane emission increased with days after transplanting and soil redox potential (Eh) decreased rapidly after flooding during the rice cultivation. The average methane emission fluxes were $5.47kg\;CH_4\;ha^{-1}day^{-1}$in flooded pre-season > 30 days, 5.04 in non-flooded pre-season < 180 days and 4.62 in non-flooded pre-season > 180. Methane emission flux was highly correlated with soil temperature and soil Eh. Rice yields showed no difference among treatments with water regime before the cultivation period.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.223-228
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• 1982

Experiments were conducted to study the interrelationships between root development of rice plant and water managements at saline paddy field where has been grown rice plant for 3 years, and to compare the root development between two fields, saline and matured. Under the conditions of non interval and two day interval flooding at saline paddy fields, root systems developed well at surface soil, however, root systems developed well and distributed evenly through surface and sub-soil at saline field where underground drainage was performed, and at matured field. Root developments at field flooded with no interval and with two-day interval were poor as compared with those of saline paddy field of underground drainage and matured field. Regardless of water managements and fields, the ratio of stunted crown roots developed after panicle fromation stage was higher than that developed at early or middle growth stage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.195-198
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• 2000

Weedy rice has typical characters such as easy shattering, dormancy, and longevity. These characters let it undergo the winter and occur year by year, It is very difficult to control weedy rice once the field have contaminated with its seeds. Therefore, the control method for weedy rice was focused on the no-tillage direct seeding in this experiment. The germination ability of seeds shattered on the soil surface in the next spring was 92.7% in weedy rice, and 4.3% in cultivated rice. The possible depth of weedy rice emergence were 1.5cm, 3.0cm and 6.8cm in no-tillage, wet seeding and dry seeding paddy field, respectively. The paddy field contaminated with weedy rice was maintained as no-tillage, and then irrigated in early spring (April 15). We could induce weedy rice on the soil to emerge with irrigation, and then kill by using non-selective herbicide, paraquat. Weedy rice was controled 92.2% of total emerged by this method. After seedling establishment of cultivated rice, molinate, thiobencarb, oxadiazon, dithiopyr, butachlor were soil-applied to suppress the emergence of weedy rice seeds buried in the soil. Oxadiazon was the most effective to repress the weedy rice among soil-applied herbicides tested. The highest control value was 96.4% as the result of combination of paraquat and oxadiazon.

• Korean Journal Plant Pathology
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• v.11 no.1
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• pp.94-97
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• 1995

In 1994, an abnormal rice growth was observed in a 0.5-ha scale farmer's field located at Chogye-Myeon, Hapcheon-Gun, Gyeongnam Province where rice cv. Hwayeongbyeo was seeded directly in dry paddy field conditions. The major symptoms were less stands per acreage, short leaf length, and hypertrophy of root tip portion. The disorder was identified as rice seeding bight caused by Rhizopus sp. The average plant stand per m2 in the infested field was 108, while it was 375 in the normal field, and leaf growth was retarded to less than one-third of healthy plant. The average leaf lengths of infected and healthy seedlings were 12.8cm and 38.9cm, respectively. When the infected seedlings were transplanted to pots, flooded-soil conditions developed no new root growth but upland conditions allowed 11.2 new roots emerging. The length of newly emerged root in infested soil was 5.3cm in upland and 7.1cm in intermediate flooding conditions. However, it was 10.9cm in non-infested soil with intermediate flooding conditions. When the plants were matured, the stem length of infected plants was reduced slightly as compared to normal plants, whereas the length of panicle was not significantly different between infected and healthy plants. The number of panicle per plant, however, greatly different with variation of infection degree. Grain quality such as the number of complete and incomplete grains per panicle, the complete grain weight per panicle, and the weight of 1000 grains was not significantly different.

• Journal of Environmental Impact Assessment
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• v.31 no.5
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• pp.296-309
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• 2022

This study investigated the mobility of inorganic elements (As, Cd, Pb, and Zn) that existed as acid extractable and reducible forms in flooded soils with a pot experiment involving rice cultivation. In general, it is known that soil inorganic elements that existed as an acid extractable form which includes exchangeable, carbonates, non-specifically sorbed, and specifically sorbed have mobility. However, the result of the experiment revealed that each inorganic elements of rice roots grown from flooded soils had different characteristics. The concentrations of Arsenic existed as both forms and the concentrations of cadmium and lead existed as a reducible form in the soils showed a high causal relationship with the concentrations of those elements in the roots of rice plants. The concentrations of zinc, an essential plant element, didn't show a causal relationship. Therefore it is necessary to consider the soil's environmental characteristics such as drained/flooded condition, oxidation/reduction condition, etc. for the mobility assessment of inorganic elements. The concentrations of the reducible form of arsenic, cadmium, and lead in flooded environment such as a paddy field should be also considered because the mobility of these elements combined with Fe/Mn increases in the reduction condition.

• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.857-868
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• 2019

A flooded rice field is one of the significant sources of anthropogenic methane (CH₄) with the intensity of the emissions dependent on management practices. Incorporation of rice straw, which is one of the organic amendments, induces the increase of methane emissions during the flooding season. In this study, we measured of methane emission according to applications of rice straw in different soil textures during a cultivation period in 2017 and 2018. The fallow treatments were non application of rice straw (NA), spring plowing after spring spreading of rice straw (SPSA), spring plowing after previous autumn spreading of rice straw (SPAA), and autumn plowing after previous autumn spreading of rice straw (APAA). The SPSA treatment emitted the highest total methane from loam soil in both 2017 (596.7 CH₄ kg ha^-1) and 2018 (795.4 CH₄ kg ha^-1). The same trend was observed in silt clay loam soil; the SPSA treatment still emitted the highest amount of methane in both 2017 (845.9 CH₄ kg ha^-1) and 2018 (1,071.7 CH₄ kg ha^-1). The lowest emission among the rice straw incorporated plots came from the APAA treatment for both soil texture types in all the seasons. The conversion factors of the SPAA were 0.79 and 0.65 from the loam and silt clay loam soils, respectively. Relatedly, the conversion factors of the APAA were 0.71 and 0.43 from the loam and silt clay loam soils, respectively. The above observations mean therefore that incorporation of rice straw early in the fallow reduces methane emissions in the main rice growing season.

• Korean Journal of Weed Science
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• v.31 no.4
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• pp.375-383
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• 2011

This experiment was carried out to confirm characteristics of macro granule (GG) for herbicidal efficacy by using remote-controlled aerial application (RCAA) to control annual and perennial weeds in rice paddy field, and phytotoxicity to rice and non target plants of formulation types. Herbicidal efficacy of GG applied by using RCAA was 93.6~96.6% in flooded direct sowing cultivation. There was no difference in phytotoxicity between the hand and the power applicator methods in terms of height, number of tiller and yield component. Herbicidal efficacy of GG applied by using RCAA was 92.7~97.3% in machine transplanting rice field. There was no difference in phytotoxicity between the hand and RCAA methods in terms of height, number of tiller and yield component. When suspension concentrate (SC) and GG were applied directly on Chinese cabbage, lettuce, cucumber, pepper, soybean and wild sesame, several symptoms of injury such as, the inhibition of growth, yellowish, leaf fall and withering was observed.